The present invention concerns fluidic control devices, in particular vortex amplifiers, in which a supply fluid flow is controlled by forming in the fluid a vortex which operates to control the supply fluid flow, the vortex being formed by the injection of a control fluid flow into the supply flow. Such a device requires a chamber in which the vortex can be formed, a supply fluid inlet and outlet to and from the chamber and at least one further inlet to the chamber arranged to direct a control fluid flow to interact with and throttle the supply fluid flow.
Vortex amplifiers can be used to control depression in radioactive containments, the amplifiers being particularly attractive to the nuclear industry as they do not comprise any moveable component parts which could require repair and maintenance. However, vortex amplifiers suffer the disadvantage that their characteristics can exhibit multivalued regions within normal flow range and this can result in instability.
The present invention seeks to provide vortex amplifiers which do not have characteristics exhibiting multivalued regions.